Butein Inhibited In Vitro Hexokinase-2-Mediated Tumor Glycolysis in Hepatocellular Carcinoma by Blocking Epidermal Growth Factor Receptor (EGFR)

Abstract

BACKGROUND Anaerobic glycolysis is an important physiological process of all cancer cells. Butein has been reported to demonstrate substantial antitumor activities in various cancers. However, the effect of butein on tumor glycolysis remains unclear. In this study, the effect of butein on tumor glycolysis and the underlying mechanism were investigated in hepatocellular carcinoma (HCC). MATERIAL AND METHODS Cell proliferation assay and anchorage-independent growth assay were carried out to evaluate the antitumor activities of butein in vitro. The effect of butein on tumor glycolysis was determined by examining the changes in glucose uptake and lactate production. Hexokinase-2 (HK-2) expression in HCC cells upon butein treatment was analyzed by Western blotting. The activity of butein on EGFR signaling pathway was studied and its potency in EGFR exogenous overexpression cells was investigated. RESULTS After butein treatment, HCC cell proliferation was significantly inhibited (91.4% in Hep3B and 88.2% in Huh-7 at 80 μM, p<0.001). Moreover, the number of colonies formed in the agar was substantially decreased (93.8% in Hep3B and 72.3% in Huh-7 at 80 μM, p<0.001). With the suppression of HK-2 expression, glucose consumption in Hep3B and Huh-7 cells decreased by 48.4% and 56.3%, respectively (p<0.01), and the lactate production also was reduced accordingly (39.5% in Hep3B and 48.6% in Huh-7, p<0.01). Mechanism investigations demonstrated that butein dose-dependently blocked the activation of the EGFR signaling pathway in HCC cells. In EGFR exogenous overexpression cells, the glycolysis suppression exerted by butein was substantially attenuated. CONCLUSIONS Butein has a substantial inhibitory effect on tumor glycolysis in HCC cells, and the glycolysis suppression exerted by butein is closely related to its effect on the EGFR signaling pathway.